Legally Insane
by OverPalaBorn
Summary: In which Izuku Midoryia has a extermely powerful quirk. What could go wrong? Well his quirk could make him insane, literally.IzuMomo! Kacchako! Quirk!Deku Sexual Themes and Strong Langauage
1. Skelton Meets CryBaby

**A/N HI! This is my first fanfic so any comments or criticism will be accepeted. I have big plans for this story and hope that you can come with me along the ride. Warning Strong Language and Sexual Themes**

**Chapter 1: Skelton Meets Crybaby**

"I'm sorry but I refuse"

A tense moment of silence befell upon the scene. A quite skinny almost skeleton like man seemed startled and a little sad at the dialogue coming from the young boy in front of him. Standing right into front of this sickly man was a green haired middle school boy who reeked of self-esteem issues and nervousness, nonetheless his words held power and conviction.

"I'm sorry if I didn't hear you correctly, what did you say, young Midoriya?" Asked the yellow man, still startled from the young mans response.

The green haired teen now identified as Izuku Midoriya gave a sigh. 'Today's been a long day, first I almost die then Sata- I mean Bakugou almost does, and now All Might is offering me plot juice but I can't take it, though it is tempting' He snapped out of his thoughts to focus on the yellow stick that is All Might who was patiently waiting for an answer.

"Truth is All Might ,thought I would like to thank you for your offer, I don't trust myself with your power I would be a dange-"

"Nonsense, I chose you to have my power because I believe it would be safe for you to use it and that you are the right person to inherit it. Even though you are quirkless that doesn't change the fact you have a heart of a hero" All Might remarked. He noticed Midoriya visible tensing when he said quirkless. 'He is quirkless right, that's what he said why would he lie about it? Or is there something more' the skelton pondered. All Might took a deep breath in and asked a question that Midoriya dreaded

"Midoriya do you have a quirk?"

Izuku looked down at the floor, he expected someone to ask that question but he never in his wildest dream or nightmare would expect it would be All Might asking it. He wanted to lie to All night liked he lied to everyone else about his quirk, but for some reason he couldn't bring himself to do it. With a heavy heart Midoriya replied.

"I do" he muttered in such a low tone, that All Might was barely able to catch it

All Mights eyebrows rose in interest "Then why did you say you were quirkless?"

"Its because I fucking hate my quirk. It makes my life worse I can't catch a break from anyone especially that little shit Bakugou. Not to mention it crushed my dream, how the fuck am I suppose to be a hero with a quirk like mine. " Izuku fired back quite aggressively. All Might was taken back by the outburst. Izuku noticed this and stopped his rambling and somehow held his head lower than it was before.

"Sometimes I scare myself" He said in a quiet voice.

Midoriya looked like he was on a verge of a panic attack. His cheeks were already wet with tears flowing from his eyes. He took shallow breaths, and for once in his life All Might found himself in a situation he couldn't punch his way out of.

"Breathe, it's okay, you don't need to tell me anything" All Might said in a calming tone to reassure the emotional mess that is the boy right in front of him.

"Thanks All Might, pardon my outburst but I'm a little stressed from today and may have overreacted, my quirk just isn't that good so I prefer just to say I'm quirkless. I'll be a hero anyways dont you worry, I'll save a lot of people and make me and moms life better." Midorit's chuckled, putting on a fake smile, hoping to fool All Might and hide the pain he had inside. Inside his head is another story, his mind was currently racing 'FUCKING STUPID DEKU , WHY NOT TELL ALL MIGHT YOUR WHOLE LIFE STORY RIGHT NOW, BETTER YET HAVE A MENTAL BREAKDOWN'

All Might felt bad for the boy, he's obviously been through a lot, and he was trying to hide all of it. While he was no therapist, he couldn't leave the boy in that type of situation. What type of hero would he be if he left a civilian in such a state.

"You could of fooled many people with that smile young Midoriya, except for me." This response startled Midoriya whose eyes widened he attempted to respond but All Might continued before he could rebuttal "As a hero I can't leave you here, while I don't expect you tell me everything. I don't think it's healthy to keep all these emotions bottled up, as a hero my job is to help, what type of hero would I be if I couldn't help you? A true hero is never afraid to ask for help" All Might stayed with a sincere tone.

"I- I-I'm sorry for trying to trick you but nobody ever cared about how I feel, or what I'm going through besides my Mom. There's a lot I have to say but I don't think I have the time, my mom is expecting me back at home soon. If you have time or interest All Might can we talk about this tomorrow at Dagobah Beach around 2:00Pm" Midoriya said half sobbing with tears flowing down his face. He hasn't talked to anyone about his feelings before so he was quite socially awkward, in fact he didn't have much friends due to his awkwardness and his quirk.

"No harm done son, and I see my schedule is free tomorrow so I might have to take you up on that offer. Truly young Midoriya" All Might said as the sun started to set behind him giving his next words even more power behind them, the words that would change young Midoriyas life and his too.

"I believe you can be a hero too"


	2. CryBabys can be Edgy too

**Chapter 2: CryBabys can be Edgy Too**

Izuku Midoriya woke up, recalling the events of the day prior. He still couldn't believe what happened. He was expecting to wake up in the morning to learn his whole encounter with All Might and the sludge villain was made up. Speaking of the Sludge Villain his mom, Inko Midoriya was so happy when he finally returned home late last night.

(Flashback)

Izuku trudged through the door, exhausted physically and emotionally from the day. His face and cheeks were already red from the tears he shed when he encountered All Might. Now he just had to figure out how to explain all this to his mom, or even better yet hide everything that happened today and wallow in his self-pity and depression in his bed.

"IZUKUUUUUUUUUU" yelled Inko from the kitchen

'No Edginess for me now' Izuku thought with a sigh before walking into the kitchen where he was greeted by his mom with a big hug and a water fall of tears.

"I was so worried honey, and after seeing what happened to Bakugou I began to worry even more. Please don't tell me you'll do that ever again Izuku , you gotta promise me." Inko sobbed out as her hug with Izuku tightened.

Izuku couldn't help and smile. His mom was one of the few reasons he found a reason to live, even when his quirk showed up his mom comforted him. His quirk! He suddenly remembered his meeting with All Might tomorrow. Before he could go to sleep he had to first take care of the sobbing mother that was in front of him.

"Mom don't worry when I become a hero this will be normal, and I can take care of myself I promise." He said with a smile, to which his mom smiled back."I'll be alright, when I'm a hero I can save a lot of people and make mine and your life better"

"Oh IZUKUUUUU you're so noble" His mom said while putting her head deeper into Izuku's chest. After a good minute she finally let go. A sense of pride and comfort washed over Inko's face, as she stared at the boy in front of him. Izuku was in every way a genius. Not to mention the fiery determination he has in his eyes, and his kind heart. Recalling what she said many years earlier when Izuku found his quirk. She opened her mouth and looked into Izuku's eyes

"Izuku I'm sorry for doubting you at first. From her on out I support all your descions, though I may not like it. Izuku honey I think you can be a hero too" exclaimed Inko with great conviction.

Izuku stood in silence and surprise. His mom despite being very nice , she always dismissed the idea of him being a hero especially because of his quirk. His mind was racing with thoughts 'First Al Might saying I can be a hero and now my mom, it's almost like the author is giving forced character development... Nah'

For the second time today Izuku let the tears flow out, nearly matching the waterfall his mom produced earlier.

"Thank you mom, that means so much to me. Don't worry I won't let anyone get in my way of becoming a hero , I'll forge my own path. I'll learn how to control my quirk. Then after that I can be the greatest hero ever saving everyone" Izuku said with tears rolling down his face.

His mom gave a small chuckle in response and said she believed in him. After a short dinner, Izuku finally retreated to his room.

(Flashback over)

Izuku gave a small smile. This happiness was erased when he looked over at his clock 9:00am. His school started at 8:00am, he was gonna be late. He immediately rushed out of bed and in a hurry got dressed, and ran downstairs to see his mom folding clothes. Izuku dashed to the food that was already prepared to him and started to wolf it down.

"MOM why didn't you wake me up" Izuku said in between bites. His mom was just sitting there calmly folding his clothes, watching his son stress out for being late to school.

"Oh you looked so peaceful. You haven't slept that comfortably in such a long time and I didn't want to ruin it" Mommy Midoriya said with a smile.

'She is right, for some reason I feel calmer, is it because the events of yesterday?' Izuku thought. He finished his food and got his stuff and opened the door before he left he called back to his mom. "Thank you Mom for everything" He said with a half-smile.

XXX

Izuku took his usual route to school, hopefully a slime villain won't come out and man handle him again. Once he reached his middle school, he was greeted by a familiar sight.

"Oi Deku you little shit, where did you go after that slime villain tried to kill me. Too scared of the media I bet" snarked a yellow demon chil- Bakugou. The yellow-haired boy was once Izuku's child hood friend but after Bakugou awakened his quirk, he thought himself above everyone, rightfully so though. Bakugou's quirk **Explosion **was one of the most powerful quirks Izuku has seen from all his analyzing. The bullying got worse when Izuku's quirk awakened, as well as its side effects.

(Flashback to School Yesterday)

"You are all getting close to graduate, I think it's time to seriously think about what you are going to do." The teacher said before letting out a sigh and looking at his students.

"You all wanna be heroes don't you" He said exasperated.

This followed by a thunderous roar from his class, with his students showing off their quirks

"Remember no quirks in school" The teacher said in a stern voice, "Why are these children so problematic, why can't they be engineers or something" the teacher said to him self quietly. Somewhere a certain dry-eyed, scarf wearing man felt the teachers pain.

"Yo teach don't group me in with these side characters. Their quirks don't have shit on mine. If anyone is gonna be a hero from this crappy school it's me. So all you extras get that through your brain." exclaimed Bakugou with a big grin.

'There's problem child number 1' The teacher thought. "Bakugou you are applying for UA right?" The teacher said checking the files on his students.

"Damn straight, ain't no other place I'm gonna go. I have to be better than All Might right, I might as well go to the best school" Bakugou added rather confidently.

"That's like the hardest school to go to"

"He has such a cool quirk"

"BAKUGOU HAVE MY CHILDREN"

The other kids in the class muttered.

"Oh Midoriya you are applying for UA too right" the teacher said. 'I kind of feel bad for Midoriya but on the other hand I don't get paid enough for that' he thought

"Izuku is going to UA?"

"His quirk is creepy, he's more like a villain"

"DEKUUUUUUUU" Bakugou yelled, "Whot he fuck said you could to go UA, not like you get in anyways. Your quirk is alright I'll give you that better than all these extras, but the side effects aren't Hero like at all" He said somewhat sincerely

Izuku just held his head down and took all the insults towards him. He knew most of the class was scared of him with the exception being Bakugou. Despite his Bakugou wasn't exactly a friend, he knew Izuku was strong but he did have a pint that his quirk's side effects were more villainous than heroic.

"All right, everyone settle down now open your books to page 78" the Teacher said tryna get control of the class.

After class was done and Bakugou bullied Midoriya a bit more. Izuku sent out to walk home where he would eventually meet All Might

(Flashback End)

"You still applying to UA?" Bakugou asked with a sigh. At this point the yellow incarnate of asshole knew that he couldn't stop Izuku from being a hero. That's the thing he hated the most about Izuku, if anything happened he would trudge through in face of adversity, even if the path would cause him and others pain.

"Y-yeah" Izuku said quietly

"Be careful and stay out of my way" Bakugou replied as he walked past Izuku to the school, brushing shoulders with him as he walked by.

Izuku stood in silence before following Bakugou to school. News of Bakugou getting attacked by a slime monster and Izuku saving him went around fast in the school. People seemed overall nice to him and some even said Good Job. However there were still people who bullied him saying that All Might have to save him or he would have died, or that Bakugou didn't need his help. However this negativity couldn't bring down Izuku's mood, for the first time in a long time he had something to look forward to, and he wasn't gonna let anyone stop it. The day went by quick and soon it was 1:50pm, and Izuku made his way to the beach

XXX

(Dagobah Beach)

Izuku arrived at the beach exactly at 2:00pm. He looked around and saw the familiar skeleton.

"Yo All Might" Izuku yelled out to the skeleton. Luckily no one was at the beach,and All Might started to walk towards him.

"Midoriya my boy how are you doing"asked All Might. He seemed to be a little bit tired but nonetheless excited to learn more about his would have been successor.

"To be honest I never felt any better. Talking with you really helped my mood, not to mention my mom " said Izuku but before he finished All Might interrupted

"Is your mom cute?" All Might asked. There was a long pause before All Might burst out laughing, which was shortly followed by a spray of blood.

"I'm joking, but it's great to have people in your life to support you. Now let's move on to business you wanted to talked about your quirk correct?" Said All Might, to which Midoriya did a nod.

"So what is your quirk?" Asked All Might.

"I think it's better if I start from the beginning" relied Midoriya. 'Cue Flashback'

(Flashback)

"Stop hurting him" yelled a 4-year-old Izuku. He was standing over another kid, protecting him. In front of Izuku was a 4-year-old Bakugou. Bakugou wast trying to bully the small kid before Izuku stepped in to protect him.

"Move our the way Deku. What are you even gonna do you don't have your quirk yet" Bakugou said menacingly as he let out little sparks from his hand. Izuku knee he was right but he couldn't let up now, what would All Might due in this situation.

"It doesn't matter Kaachan, I don't need a quirk" Izuku said with slight confidence before looking back at the child he was protecting. "Don't worry, I am here" he said with a smile.

"Don't look away from a fight idiot" Bakugou said before sending with a right hook at Izuku. That hook never hit Izuku. Instead it hit a solid wall of black energy with red lightning crackling around it. But it disappear before he could think about it any more. His fist connected with Izuku's face and sent him to the ground on his butt. Instead of crying like the **crybaby** Izuku was he stood there with a blank expression in his eyes

"Oi Deku the fuck was that black thing. Is it your stupid quirk" Bakugou said mockingly but his words fell on deaf ears as heard small chuckles from the Deku in front of him.

"Kaachan hurt me. **That means I can hurt him back**" Izuku said as he grinned insanely. Tendrils of the black energy sprouted from Izuku's back. Red lightning was swarming around the tendrils and Izuku. Without warning one of the tendrils shot forward to hit Bakugou, luckily Bakugou was able to dodge the attack.

"Dek- I mean Izuku what the fuck" Bakugou said, this sudden change in personality was startling to Bakugou, the kid Izuku was trying to protect was long gone, it was only him and Izuku by themselves. 'Fuck I didn't think I needed to do this' Bakugou thought before he put his right arm up and sent a red explosion up to the sky, a flare signal, hoping that someone would come.

"What's wrong Kaachan **we are just having fun right** " Izuku laughed his grin getting wider.

Bakugou finally got a good look at Izuku and could notice the difference imeddiatley. While most of his physical attributes stayed the same , there was a whole change in Izuku's demeanor. Gone was the shy kid, in front of him was an arrogant, insane kid who was grinning manically with a deranged look in his eyes.

"Get the fuck away from me. Don't make hurt you, take a step back" The demolitionist said quite shaken by the change. Izuku let off another crazy laugh before he started taking a small step forward. Panicking Bakugou shot off the largest explosion he could muster. In that moment the laughter of Izuku went silent, as Bakugou realized his actions.

'Oh shit I just killed Deku. Fuck I can't be a hero now. What would Auntie Inko sa-' His thoughts were cut short once the smoke cleared away and he saw what his target was.

Instead of a bloody burnt Deku on the floor, there was a huge black wall of energy with the familiar red lightning crackling around it. The wall shrunk untill Bakugou could see Deku again. Perfectly unscathed .

"Come on Kaachan do it, **HIT ME AGAIN"** Izuku said laughing. This froze Bakugou in terror, he ranked his strongest explosion and didn't seem hurt at all. Bakugou watched as the black tendrils that sprouted from Izuku's back rose up and curled, getting ready to hit him.

'Damn It legs why won't you move' Bakugou thought, he couldn't get himself to move out-of-the-way of his attack, when suddenly a miracle happened. The tendrils calmed and retreated to Izuku's back as he fell over taking in deep breaths of oxygen. Bakugou looked in interest at Izuku, instead of the crazy child who was about to kill him, it was the normal shy perfectly sane Deku.

"Kaachan I'm sorry, I don't know what happened" Izuku said in between breaths. He was sweating furiously and his face looked like he was sincerely sorry for what happened.

"It's fine Izuku, you just lost control of your quirk for a second, it happened to me when I first used mine. Of course your quirk isn't as cool as mine" Bakugou said returning to his old self flashing a snarky grin. In which Izuku smiled back, seeming relieved the thing was over.

"Actually it seems the Green Problem Child is stronger than you Blasty" said an unknown voice "Also I would like to tell the green child, get your quirk registered. A quirk that powerful can be dangerous if untrained." The owner of this voice was a young man, he had black hair, and dry eyes. He seemed very tired and was wearing a plain-looking scarf around his neck.

"Hey who the fuck you think you are?" Asked Bakugou aggressively.

"Call me Eraserhead and you should thank me in the one who stopped your friend over there with my quirk." Said the man rather blandly, "anyways I don't have time to stick around, stay out of trouble" and with that the man started to walk away.

None of the boys made a visible action to follow him. They both said their goodbyes to each other and decided to head back home.

XXX

"MOMMMMMMMM I'm home" Said Izuku as he reached his house, it's been a long day but he couldn't wait to register his quirk and figure out what it is.

"Hey Izuku" Said Inko but she quickly noticed her sons state and ran towards him. "What happened are you okay, who did this to you. Was it that Katsuki again or was it someone new?" His mom started rambling

"I found my quirk mom" Izuku said smiling with tears going down his face. His mom smiled back and told him to get ready they needed to bust the hospital to get it ready

XXX

A few blood test later and DNA samples as well as test the doctors finally identified Izuku's quirk.

"Your quirk is very powerful young man. However it has one main drawback" Said the doctor to the young child and the mother infront of him. "Do you want the bad news or the good news first" he asked.

"Good news first Mr.Doctor sir" Said Izuku, he was so ecstatic to learn about his quirk, hopefully he could be like All Might.

"Well it seems your son is able to produce and manipulate a black energy from his body. This energy is very strong and can be used to create constructs or strengthen his body and stamina.His quirk also grows stronger the more he uses it, so when he is in a fight he will grow stronger as time progresses. This energy will not only grow stronger through training, but your control over it will also increase. There's not that much physical drawbacks from using your quirks. In a sense the only that can stop you now is your own training and your creativity with the quirk." The doctor said smiling , in the inside however he knew the drawbacks of such a powerful quirk, and judging by the All Might merchandise in the kids hand he won't take to it too well.

"Wow Izuku isn't that so cool. You have a powerful quirk" Said Inko happy for her son to have a powerful quirk. "But I wonder how did Izuku get this quirk the chances for something like to happen are near impossible right, I mean I have minor telekinesis and my husband breathes fire"

"I was also surprised when I saw this but digging into you and your husband's family tree we have a plausible explanation on what happened" The doctor said, "As you know quirks can sometimes skip generations, sometimes multiple generations, as long as someone in your family had a certain quirk, there is a chance you can have that quirk. As it shows one of your ancestors Inko seems to of had a quirk that lets them produce and manipulate energy at a high level but with major physical drawbacks. Your husband on the other hand had a great-uncle whose quirk was a sort of self regeneration quirk. While near impossible, these two quirks somehow merged perfectly to create your sons quirk." Finished the doctor.

"Interesting, So whats the bad news about my sons quirk" Asked Inko.

The doctor let out a large sigh, "I'm gonna put this bluntly we still aren't sure why your sons quirk drawback is the way it is. In exchange for all this power, your son mental health deteriorates when he uses his quirk"

Inko and Izuku both looked shock, then Izuku spoke up "Oh is it like one of those quirks where the person gets stupid after using it, right" he said optimistically.

"It's not like that while when your quirk is not turned on you will be perfectly fine. When you sue your quirk while you intelligence level will remain the same, you will slowly become more insane, the stronger your quirk becomes the stronger the after effects will be. Like I said we don't know why your quirk operates like this, but I am sorry. I don't think you can be a hero."The doctor said in a sad tone.

Izuku and Inko were heartbroken, the All Might figurine falling out of his hand.

"There surely must be someway to remedy the side effects, therapy would help right" Inko pleadingly said to the doctor.

"I don't think therapy can help as said these side effects only happen when his quirk is active, if I'm being honest the best way to remedy this is to make your quirk usual very small, we don't want another accident" Said the doctor, "By the way we still need a name for the quirk"

"**Malice**, it's gonna be called **Malice**" Izuku said immediately, his face carried a sad expression, the doctor and his mom stared at him for a bit , then the doctor went and finished his registration, printed out a copy and sent the two on their way home.

'I know I can be a hero' thought Izuku as he left the hospital

(Flashback end)

"And that's how I got here" Said Izuku, he shed a few tears while recalling his story. But he knew everything was going to be better now that All Might was here. All Might was dumbfounded at this kid, he's been through so much but to go through this at such a young age and still carry on

'Truly this kid has a heart of a hero' All Might thought, before opening his mouth to speak "I see, you have an interesting quirk, but you could still be a hero with it. In fact I know you can be a hero with it. But is that the only reason you wanted me here, is to tell someone about your quirk or is there more?"

"Truth is there's more I wanted to ask from you if you had time. You see I want to apply for UA and it's nearly impossible for me to do it quirkless" Said Izuku

"You don't mean young Midoriya" All Might replied catching on to what the young man was trying to get at. Izuku shook his head yes before smiling,

"That's why I wanted you here, I want to learn how to control my quirk"


End file.
